Not the OP says "formail" not "formmail"...
man formail
[snip]
DESCRIPTION
formail is a filter that can be used to force mail into mailbox format,
perform From ' escaping, generate auto-replying headers, do simple
header munging/extracting or split up a mailbox/digest/articles file.
The mail/mailbox/article contents will be expected on stdin.
This isn't the same as formmail, maybe the OP needs to tell us which he really meant. B-)
Cheers
Dave.